Apparatus and method for increasing upstream capacity in a broadband communications system

ABSTRACT

A method for providing enhanced broadband services over a communications network includes the steps of: receiving from the communications network at least first signals in a first frequency band, the first signals comprising programming material that has been converted from a second frequency band and/or material originally generated in the first frequency band to be converted to the second frequency band, the first and second frequency bands being non-overlapping; translating one or more first signals from the first frequency band to the second frequency band; and combining the one or more first signals translated to the second frequency band with the first signals in the first frequency band to generate combined programming material comprising one or more signals in the first frequency band and one or more signals in the second frequency band for reception by receiving location equipment.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. provisional application Ser.No. 61/324,458, filed on Apr. 15, 2010, the complete disclosure of whichis expressly incorporated herein by reference in its entirety for allpurposes.

FIELD OF THE INVENTION

The present invention relates generally to the electrical, electronic,and computer arts, and more particularly relates to delivery ofprogramming content and services to subscribers via a communicationsnetwork.

BACKGROUND OF THE INVENTION

In existing cable systems, it is desirable for cable service providersto supply not only broadcast programming content but also to supplysecondary broadband data services to subscribers. Such broadband dataservices may be used, for example, to provide Internet access, streamingvideo, Voice over Internet Protocol (VoIP) telephony, etc., tosubscribers.

With the continual push to extend data communications capacity andfeatures of broadband services, there are significant modifications tothe existing infrastructure that are required in order to support suchextended data communications capacity and features, including, but notlimited to, replacing existing copper wiring with optical fiber cable,replacing headend communications equipment capable of operating atenhanced data rates or in extended frequency spectrums, and retrofittingcustomer premises equipment (e.g., set-top boxes or set-top terminals)for supporting the enhanced broadband services. Unfortunately, themodifications to the existing broadband service that are required todeliver such enhanced features and/or broadband capacity are oftendisruptive to subscribers and are generally cost-prohibitive to theservice provider.

SUMMARY OF THE INVENTION

Techniques are provided for facilitating ultra high-speed broadbandservice (e.g., 1 gigabits per second (Gbps) upstream capacity or higher)using existing hybrid fiber-coax (HFC) network wiring while providingbackwards compatibility with legacy customer premises equipment (CPE) inoperative communication with the network. In this manner, embodiments ofthe invention provide a cost-effective solution for migratingsubscribers to the enhanced broadband service without disrupting serviceto legacy subscribers who do not desire such enhanced services. Toaccomplish this objective, embodiments of the invention preferablyinclude a gateway apparatus couplable between the HFC network and CPEwhich is operative to receive downstream signals in an enhancedfrequency spectrum high enough to support a prescribed upstreamcapacity, and yet maintain legacy service functionality.

In accordance with one embodiment of the invention, a method forproviding enhanced broadband services over a communications networkincludes the steps of: receiving from the communications network atleast first signals in a first frequency band, the first signalscomprising programming material that has been converted from a secondfrequency band and/or material originally generated in the firstfrequency band to be converted to the second frequency band, the firstand second frequency bands being non-overlapping; translating one ormore first signals from the first frequency band to the second frequencyband; and combining the one or more first signals translated to thesecond frequency band with the first signals in the first frequency bandto generate combined programming material comprising one or more signalsin the first frequency band and one or more signals in the secondfrequency band for reception by receiving location equipment.

In accordance with another embodiment of the invention, an apparatus forinterfacing between one or more customer premises devices and acommunications network includes an interface couplable to thecommunications network and operative to receive at least first signalsin a first frequency band, the first signals including programmingmaterial that has been converted from a second frequency band and/ormaterial originally generated in the first frequency band to beconverted to the second frequency band. The first and second frequencybands are non-overlapping. The apparatus further includes a frequencyconverter coupled to the interface and operative to translate one ormore first signals from the first frequency band to the second frequencyband. A combiner in the apparatus is coupled to the frequency converterand to the interface. The combiner is operative to combine the one ormore first signals translated to the second frequency band with thefirst signals in the first frequency band to generate combinedprogramming material including one or more signals in the firstfrequency band and one or more signals in the second frequency band forreception by customer premises devices.

In accordance with yet another embodiment of the invention, a gatewayapparatus is provided for interfacing between a broadband communicationsnetwork and at least one customer premises device. The gateway apparatusis operative: (i) to receive downstream signals in an enhanced frequencyspectrum high enough to support a prescribed upstream data capacity; and(ii) to restore upstream out-of-band functionality between the at leastone customer premises device and the broadband communications network.

One or more embodiments of the invention, or elements thereof, can beimplemented in the form of a computer product including a tangiblecomputer readable recordable storage medium with computer usable programcode for performing the method steps indicated. Furthermore, one or moreembodiments of the invention or elements thereof can be implemented inthe form of a system (or apparatus) including a memory, and at least oneprocessor coupled to the memory and operative to perform exemplarymethod steps. Yet further, in another aspect, one or more embodiments ofthe invention or elements thereof can be implemented in the form ofmeans for carrying out one or more of the method steps described herein;the means can include (i) hardware module(s), (ii) software module(s),or (iii) a combination of hardware and software modules; any of(i)-(iii) implement the specific techniques set forth herein, and thesoftware modules are stored in a tangible computer-readable recordablestorage medium (or multiple such media).

These and other features and advantages of the present invention willbecome apparent from the following detailed description of illustrativeembodiments thereof, which is to be read in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are presented by way of example only and withoutlimitation, wherein like reference numerals indicate similar elementsthroughout the several views, and wherein:

FIG. 1 depicts an illustrative allocation of frequency bands in afrequency spectrum from 150 MHz to 750 MHz for transmission of variousidentified types of programming material in a conventional broadcastcable television system;

FIG. 2 is a block diagram depicting an illustrative broadbandcommunications system in which principles of the present invention maybe embodied;

FIG. 3A is a block diagram depicting at least a portion of an exemplarybroadband communications system including a gateway apparatus, accordingto an embodiment of the present invention;

FIG. 3B is a block diagram depicting at least a portion of an exemplarybroadband communications system including a gateway apparatus, accordingto another embodiment of the present invention;

FIG. 3C is a block diagram depicting at least a portion of an exemplarybroadband communications system including a simplified gatewayapparatus, according to an embodiment of the present invention;

FIG. 4 is a block diagram depicting an exemplary broadbandcommunications system including a gateway apparatus with integratedamplifier, according to an embodiment of the present invention;

FIG. 5 is a block diagram depicting an exemplary broadbandcommunications system including a simplified gateway apparatus,according to an embodiment of the present invention; and

FIG. 6 is a block diagram depicting an exemplary processing system,according to an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Principles of the present invention will be described herein in thecontext of illustrative embodiments of a gateway model architecturesuitable for use, for example, in a hybrid fiber-coax (HFC) network, orother communications system. It is to be appreciated, however, that theinvention is not limited to the specific apparatus and methodsillustratively shown and described herein. Furthermore, while aspects ofthe present invention are particularly well-suited for use inconjunction with data-over-cable service interface specification(DOCSIS) and Digital Audio Visual Council (DAVIC) communicationsprotocols, the invention is not limited to use with such protocols, orto any other standard or non-standard communications schemes. Rather,aspects of the invention are directed broadly to a cost-effectivesolution for beneficially providing enhanced broadband datacommunications over an existing broadband network, while advantageouslyproviding compatibility with legacy customer premises equipment (CPE),or alternative receiving location equipment, such as, for example,set-top boxes (STBs) or set-top terminals (STTs). In this manner,aspects of the invention facilitate ultra high-speed broadband service(e.g., 1 Gbps upstream capacity or higher) using existing HFC networkwiring while providing backwards compatibility with legacy CPE inoperative communication with the network.

It will become apparent to those skilled in the art given the teachingsherein that numerous modifications can be made to the embodiments shownthat are within the scope of the present invention. That is, nolimitations with respect to the specific embodiments described hereinare intended or should be inferred.

In a standard cable television (CATV) system, programming materialcorresponding to various program channels, regardless of the format(e.g., analog or digital), is generally transmitted over a multi-channeldelivery network (e.g., CATV network) including one or more transmissionchannels. The term “transmission channel” as used herein is intended torefer broadly to a designated frequency band through which a transportstream comprising program material and/or data is conveyed. In oneembodiment, a transmission channel may comprise, for example, a 6Megahertz (MHz) frequency band, although the invention is not limited toany specific frequency band. The term “program channel” as used hereinis intended to refer broadly to the source of programming material orthe service for use by a consumer (e.g., CATV subscriber).

Programming material may be transmitted in various formats, including,for example, analog program channel material, digital program channelmaterial, video-on-demand (VOD) services, etc. In order to accommodatethese formats, a designated broadcast frequency spectrum is divided intovarious allocated frequency bands, each frequency band corresponding toa given programming material format.

FIG. 1 depicts an illustrative allocation of frequency bands in afrequency spectrum from 150 MHz to 750 MHz for transmission of variousidentified types of programming material in a conventional broadcastcable television system. Analog program channel material may beallocated to a first portion of the frequency band, which may be ananalog TV band 103, ranging from about 50 MHz to about 550 MHz, digitalprogram channel material may be allocated to a second portion of thefrequency band, which may be a digital TV band 104, ranging from about550 MHz to about 650 MHz, and VOD program material may be allocated to athird portion of the frequency band, which may be a digital on-demand(DOD) band 107, ranging from about 650 MHz to about 750 MHz. Out-of-band(OOB) data communications, including, for example, control signaling,may be allocated to yet another portion of the frequency band.

FIG. 2 is a block diagram depicting an illustrative broadbandcommunications system 100, e.g., a cable TV system, in which principlesof the invention may be embodied. The system 100 includes a headend 105operative to receive, among other things, programming materialsattributed to various program channels, and provides TV broadcast andother services, e.g., VOD services, to users at different userlocations, including user locations 158-1 through 158-L, which may bereferred to collectively as 158, connected to the same service area node150, where L represents an integer greater than one. Although only oneservice area node 150 is shown, system 100 may include a plurality ofservice area nodes, with each service area node functioning as aninterface between corresponding user locations coupled thereto (e.g.,150-1, 158-L) and HFC network 140. Each user location (e.g., 158-1)preferably includes a reception gateway 675 connected to one or moreSTTs or STBs. A television or other display device is preferablyconnected to the STT for display of selected programming material. Forexample, user location 158-1, which may be a home, includes gateway 675which may be installed inside or outside the home, and is connected toSTT 676.

The programming materials are delivered from headend 105 to userlocations 158 through “in-band” transmission channels provided by HFCcable network 140. In accordance with the DOCSIS, these transmissionchannels provided by the HFC network may comprise 6 MHz channels (US) or8-MHz channels (Europe) located in the 47-862 MHz band allocated fordownstream communications of the programming materials from headend 105to user locations 158-1 to 158-L. Quadrature amplitude modulation (QAM)modulator bank 168 in hub 120 preferably modulates the downstreamcommunications onto selected in-band transmission channels in accordancewith a well known QAM scheme.

In addition to the in-band channels, data may be communicated downstreamfrom headend 105 to user locations 158 via one or more forward datachannels (FDCs). FDCs, sometimes referred to as “out-of-band” (OOB)channels, are often employed to transport control signaling data and/orother data, e.g., system messages, etc., to user locations 158. In oneembodiment, the FDCs may populate the 54-130 MHz band of a coaxialcable. Quadrature phase-shift keying (QPSK) modem pool 169 in hub 120modulates downstream data onto selected FDCs in accordance with a wellknown QPSK scheme.

Data may be transmitted upstream from user locations 158 to headend 105via one or more reverse data channels (RDCs), which populate a reversepassband, e.g., 5-40 MHz band, of a coaxial cable. Data conveyed by theRDCs is modulated in accordance with the QPSK scheme. QPSK modem pool169 receives the QPSK signals in the RDCs and performs any necessarydemodulation before transmitting the signals to headend 105.

An STT 676 at a user location 158-1 may utilize an RDC for sending dataincluding, e.g., user data, messages, etc., to headend 105. Using acontention-based access mechanism established by the DAVIC, a standardsetting organization, each STT can share an RDC with other STTs in thenetwork. This mechanism enables an STT to transmit upstream messageswithout a dedicated connection to a QPSK demodulator. As also specifiedby DAVIC, for communications purposes, a network controller 125 in theheadend 105, and STTs 676, are preferably individually identified byunique Internet protocol (IP) addresses assigned thereto. In thisinstance, e.g., STT 676 and gateway 675 may each be identified by an IPaddress.

In this illustration, headend 105 includes a digital TV program receiver109, an analog TV program receiver 110, an analog signal processor 111,a VOD server 119, network controller 125, a switching unit 117, and aresource manager 166. In a conventional manner, digital TV programreceiver 109 receives TV programming material in digital format (e.g.,an MPEG-2 format) from one or more digital program channel sources.Receiver 109 then provides to switching unit 117 the digital TV programstreams, which may have been multiplexed to form one or more digital TVtransport streams. Each transport stream may be identified by a uniquetransport stream identification (TSID). Each TV program stream within atransport stream may be identified by a program stream ID (PID) or otheridentifier.

Analog TV program receiver 110 receives, in a conventional manner,traditional analog TV programming material from one or more analogprogram channel sources. For example, programming material from sixtyanalog program channels may require about 400 MHz bandwidth to conveysame. To that end, the received analog programming material is fed toanalog signal processor 111 wherein an analog-to-digital (A/D) converter(not explicitly shown) digitizes the analog material in a conventionalmanner. The digitized analog TV programming material is encoded using aMPEG-2 encoder (not explicitly shown), or other encoding means, toeffect data-compression thereof. The resulting MPEG-2 program streamscontaining the analog material may be encrypted in accordance with aconventional data encryption scheme to secure the programming content.The output of analog signal processor 111, which may be referred to as“digitized analog TV transport streams,” is fed to switching unit 117.

VOD server 119, under the control of network controller 125, generatesdigital program streams containing programming material requested byusers, e.g., movies requested through a VOD service. In one embodiment,VOD server 119 may generate transport streams, each comprising one ormore program streams. The transport streams generated by VOD server 119,hereinafter referred to as “VOD transport streams,” are fed to switchingunit 117. Network controller 125, among other functions, preferablyreceives requests from users for VOD services and, in response, causesVOD server 119 to generate one or more VOD transport streams containingthe requested programming material.

Under the control of network controller 125, the transport streams fromdigital TV program receiver 109, analog signal processor 111, and VODserver 119 are switched by switching unit 117 to selected modulators inQAM modulator bank 168 in hub 120. The selected modulators modulate therespective transport streams onto various in-band transmission channels,e.g., according to a prescribed frequency band allocation. For example,with reference again to FIG. 1, DOD band 107 ranging from 650 MHz to 750MHz may be allocated for the transmission of VOD transport streams, anddigital TV band 104 ranging from 550 MHz to 650 MHz may be allocated fortransmission of digital TV transport streams. However, because of theabove-described processing by analog signal processor 111, the digitizedanalog TV transport streams require only a narrow portion of the analogTV band 103 ranging from, for example, 150 MHz to 190 MHz, as opposed tothe entire analog TV band ranging from 150 MHz to 550 MHz, fortransmission of the same amount of analog TV programming material.

Resource manager 166 may be operative to assign an unused transmissionchannel within band 107 for transmitting the aforementioned VODtransport stream, especially when no transmission channels in band 103are available. Manager 166 informs network controller 125 of such anassignment. Network controller 125 directs switching unit 117 to switchthe VOD transport stream to the proper modulator in QAM modulator bank168 to modulate the VOD transport stream onto the assigned transmissionchannel.

With an ever-increasing number of program channels and use of on-demandservices (e.g., movies-on-demand and subscription VOD services), thereis a continual push for additional bandwidth to deliver such programmingmaterial and other services. Aspects of the invention are directed tomore effectively utilizing the limited network bandwidth for providingenhanced broadband programming and services, including 1 Gigabits persecond (Gbps) symmetrical broadband service (i.e., 1 Gbps upstream anddownstream). Existing HFC networks do not have adequate upstreamcapacity to provide such service.

Possible solutions to increasing the upstream capacity of an existingHFC network include, but are not limited to, replacing the traditionalcopper wire with optical fiber, allocating additional spectral space inthe passband, and extending the passband to place new upstream serviceabove the current spectrum. These proposed solutions are, however,either prohibitively expensive, too complex, or would require extensiveretrofitting, and are therefore undesirable.

DOCSIS 1.x and 2.0 specifications support an upstream frequency range of5 MHz to 42 MHz (65 MHz for Euro-DOCSIS) and a downstream frequencyrange from 88 MHz to 860 MHz. (See, e.g., “Data-Over-Cable ServiceInterface Specifications, DOCSIS 2.0, Radio Frequency InterfaceSpecification,” CM-SP-RFIv2.0-C02-090422, Apr. 22, 2009, the disclosureof which is incorporated by reference herein in its entirety for allpurposes). The DOCSIS 3.0 specification, extends the upstream frequencyrange from 5 MHz to 85 MHz and the downstream frequency range from 108MHz to 1002 MHz. (See, e.g., “Data-Over-Cable Service InterfaceSpecifications, DOCSIS 3.0, Physical Layer Specification,”CM-SP-PHYv3.0-I08-090121, pp. 20-21, Jan. 21, 2009, the disclosure ofwhich is incorporated by reference herein in its entirety for allpurposes).

The band of frequencies between the maximum upstream range and theminimum downstream range may be referred to as the “diplexer crossover,”“crossover band,” “crossover region,” or “crossover point;” these termsmay be used interchangeably herein. Raising the crossover point isbeneficial for future spectrum re-allocation and avoiding known badfrequencies on the upstream. In implementing this proposed shift in thecrossover point (e.g., from 42/54 MHz to 85/108 MHz), a possibility forcustomer premises equipment (CPE) overload may occur; specifically,there is a concern as to whether or not current CPE such as STBs and TVsets can handle a potentially high level of “noise” generated by a modemoperating at 40 MHz or higher. For example, a National Television SystemCommittee (NTSC) TV set intermediate frequency (IF) is about 41-47 MHz,and upstream signals in this range may cause interference with TVs andVCRs connected directly to the cable. Furthermore, in order toaccommodate this shift in the crossover point, one or more components inthe forward or reverse signal paths, such as, for example, diplexfilters, may require replacement.

The term “forward signal path” as used herein is intended to refer tothe direction of radio frequency (RF) signal flow away from the headendtoward the end user (i.e., downstream). Likewise, the term “reversesignal path” as used herein is intended to refer to the direction of RFsignal flow toward the headend away from the end user (i.e., upstream).

A diplex filter essentially allows the forward signal path and thereverse signal path to use the same coaxial cable without interference.Typically, one diplex filter is used on the input of a forward signalamplifier and output of a reverse signal amplifier and another diplexfilter is used on the output of the forward signal amplifier and inputof the reverse signal amplifier. A diplex filter is a three-port passivedevice comprising a high pass filter and a low pass filter joined at acommon port. In this arrangement, the diplex filters are used with thedistribution amplifier and reverse signal amplifier to separate theforward traveling high frequency broadband television channels and thereverse traveling low frequency data or monitoring channels.

Legacy STBs are operative to receive certain channels such as, forexample, program guides—so-called “forward control (DAVIC) carrier.”However, these legacy STBs are only capable of receiving that carrier upto about 130 MHz. Hence, moving the crossover point to 85/105 MHz (as inthe case of DOCSIS 3.0) would still enable legacy STBs to receive theaforementioned forward control carrier. Unfortunately, however, themaximum upstream frequency range of 85 MHz is insufficient to achieve adesired 1 Gbps upstream capacity. Consequently, a substantially higherfrequency crossover point is required. For example, one way to achieve a1 Gbps upstream capacity is to extend the maximum upstream frequencyrange to 200 MHz and the minimum downstream frequency range to 258 MHz,so that the new crossover region lies between 200 MHz and 258 MHz (i.e.,a 200/258 MHz split). By utilizing this approach, legacy STBs would nolonger be able to receive the forward control carrier, and thus the200/258 MHz split would render legacy STBs obsolete. Moreover, replacingor retrofitting all STBs would involve a significant capital investmentand would therefore be undesirable.

One possible solution for restoring the capability of legacy STBs toreceive the forward control carrier would be to demodulate the forwardcontrol carrier and to translate the information conveyed therein to ahigher frequency carrier. This can be accomplished in the home (enduser), such as by the STB, assuming the STB is capable of receiving thedemodulated signal. At the CPE, a separate device would be placed infront of the STB (e.g., between the STB and the HFC network) thatdemodulates the information from the higher frequency carrier andremodulates it on a channel that the legacy STB is operative to receive.This solution, however, is relatively complex and has its own costsassociated therewith. It is to be understood, however, that according toother embodiments it is not necessary to demodulate the forward controlcarrier signal.

Another problem with the 200/258 MHz split migration is the loss oflow-frequency analog channels; for example, channels 2 through 29.Although the programming conveyed on these channels can be duplicatedand shifted to higher channels, for example, channels 30 through 64,respectively, in nodes ready to upgrade, there is substantialdesirability that these channels remain at their original allocations.

The present invention, in one or more embodiments thereof, overcomesdisadvantages of the aforementioned approaches by providing an enhancedbroadband communications system (e.g., ultra high speed data service,Internet Protocol television (IPTV) service, etc.) that is fullycompatible with legacy CPE. In this manner, techniques of the inventiondescribed herein beneficially provide a cost-effective solution formigrating subscribers to enhanced features of the broadband service whendesired without necessitating the replacement of all STBs in the networkor disrupting service to those subscribers who do not opt for suchenhanced services.

To accomplish this, embodiments of the invention advantageously move theupstream/downstream split point to a frequency high enough in thespectrum to support a desired upstream data rate of the enhancedbroadband service. Upconversion may be used to move the split point tothe higher frequency. Subsequently, downconversion is used to restorethe analog channels and forward control (DAVIC) carrier to theirrespective original allocations. Additionally, signals originallygenerated in a higher frequency band and intended for use by legacycustomer premises devices may be downconverted for reception by thelegacy devices using the inventive techniques. By way of example onlyand without loss of generality, in accordance with one embodiment of theinvention, the maximum frequency of the upstream frequency range ismoved to 200 MHz and the minimum frequency of the downstream frequencyrange is moved to 258 MHz, thereby establishing a 200/258 MHz splitpoint. This split point provides sufficient spectrum to support anupstream data rate of about 1 Gbps. Other split points supporting higher(or lower) upstream data rates are similarly contemplated by theinvention.

Throughout the description herein, it is to be understood that thepresent invention is not limited to the specific split point of 200/258MHz, or to any particular split point. Moreover, the principles of theinvention are not limited to any specific frequency or frequency band(s)of operation. For example, features of the invention can be used toprovide advantages (e.g., enhanced upstream data capability) overconventional approaches using the split point of 85/105 MHz specified inDOCSIS 3.0. Although in using this 85/105 MHz split point analogchannels 2 through 6 would be lost, these channels can be restored usingtechniques of the present invention described herein. Hence, it is to beappreciated that the downconversion bands are essentially flexibleaccording to aspects of the invention.

With reference now to FIG. 3A, a block diagram depicts an exemplarybroadband communications system 300, e.g., a cable TV system, accordingto an embodiment of the invention. It is to be appreciated thatreferences made to specific frequencies and/or frequency ranges (orbands) are presented herein merely by way of illustration only and isnot intended to limit the invention in any way. Rather, one skilled inthe art given the teachings herein will understand that alternativefrequencies and/or frequency ranges may be employed as desired inaccordance with other embodiments to accommodate further applications ofthe inventive techniques.

As apparent from FIG. 3A, system 300 comprises a headend or hub(preferably residing indoors but may alternatively reside outdoors) incommunication with CPE 304, which includes one or more legacy devices(e.g., legacy STB) in the home (customer premises), via an HFC network306, or an alternative networking arrangement. A gateway apparatus(e.g., modem) 308, which preferably resides in the home, is coupledbetween the CPE 304 and the HFC network 306 and functions, at least inpart, as an interface between one or more legacy devices in the home andthe HFC network or hub. A more detailed operation of the gateway modem308 will be described herein below.

A downstream signal path will now be described in accordance with anembodiment of the present invention. As previously stated, in order toachieve a 1 Gbps upstream capacity, the signal frequency spectrum ispreferably extended such that a maximum upstream frequency range isincreased from 42 MHz to 200 MHz and the minimum downstream frequencyrange is increased from 54 MHz to 258 MHz, so that the new crossoverregion lies between 200 MHz and 258 MHz (i.e., 200/258 MHz split point).In this approach, analog channels 2-30 and the forward control (DAVIC)carrier are treated as one large block. The entire spectrum can be movedto the new 200/258 MHz split point using known upconversion techniques(block upconversion). To accomplish this, headend or hub 302 preferablyincludes an upconverter 310 (e.g., block upconverter (BUC)) operative toreceive as an input signals in a 54-258 MHz spectrum and to generate asan output corresponding upconverted signals in a modified 258-454 MHzspectrum. These upconverted signals are then passed to the HFC network306.

Gateway modem 308 is operative to receive the upconverted signals fromthe HFC network 306. Specifically, a network interface, which may be adiplex filter 312, in the gateway modem 308 is operative to receive theupconverted signals from the HFC network 306. As noted above, a diplexfilter, also referred to as a “diplexer,” is generally a passive deviceadapted to implement frequency domain multiplexing, thereby allowing theforward (e.g., downstream) signal path and the reverse (e.g., upstream)signal path to be conveyed on the same coaxial cable withoutinterference.

More particularly, a diplex filter is a three-port device; two ports aremultiplexed onto a third port. Each of the ports is preferablybidirectional. The signals on first and second ports (e.g., ports L andH) occupy disjoint (i.e., non-overlapping) frequency bands. Accordingly,the signals on ports L and H can coexist on the third port (e.g., portS) without interfering with one another. Often, the signals on port Lwill occupy a lower frequency band and the signals on port H will occupya higher frequency band. In this scenario, the diplex filter comprises alowpass filter connecting ports L and S and high pass filter connectingports H and S. Ideally, all the signal power on port L is transferred tothe S port and vice versa. Likewise, ideally all the signal power onport H is transferred to port S and vice versa.

Diplex filter 312 divides forward and reverse signals received from andtransmitted to, respectively, the HFC network 306; downstream signals ina frequency range greater than 258 MHz received from the HFC network,coupled to port S of the filter, are sent to port H and upstream signalsin a frequency range less than 200 MHz are received on port L of thefilter and sent to port S.

Downstream signals on port H of diplex filter 312 are sent to a firstradio frequency (RF) splitter 314 which is operative to generate atleast two signals having substantially equal amplitudes relative to oneanother. As will be understood by those skilled in the art, a splitteris essentially a passive device which receives an input signal andgenerates multiple output signals with specific phase and amplitudecharacteristics. A zero-degree splitter ideally generates output signalsthat are of equal amplitude, have zero degrees of phase differencerelative to one another and relative to the input signal, and haveinfinite isolation between the output signals. There is a theoreticalinsertion loss associated with a splitter. For example, for a splitterhaving two input ports, a theoretical insertion loss of 3.0 dB isexpected between the input signal and either output signal. Moreover,since a splitter is a reciprocal passive device, it may be utilized as acombiner as well simply by applying each signal singularly into each ofthe splitter output ports. The vector sum of the signals will appear asa single output at the splitter input port. The power combiner willexhibit an insertion loss that varies as a function of the phase andamplitude relationship of the signals being combined.

One of the split signals, S1, generated by first RF splitter 314 is sentto a second RF splitter 316 where signal S1 is split again to generatethird and fourth signals, S3 and S4, respectively. Signal S3 is suppliedto an advanced DOCSIS receiver 318 (which may be referred to as a“DOCSIS Advanced MAC (media access control) and PHY (physical layer)(A.M.P.)” receiver or, informally, a “DOCSIS 4.0” receiver) which isoperative to feed the received downstream signal S3 to a front-end(either digital or analog front end) that selects a desired channel,amplifies it and converts it down to a baseband signal.

Although the type of modulation scheme(s) employed by the DOCSIS A.M.P.receiver 318 is not critical, the receiver is preferably operable usingorthogonal frequency division multiplexing (OFDM) or othersub-channelization (i.e., anything that employs multiple carriers)modulation schemes (e.g., QAM or QPSK), in non-limiting embodimentsthereof. In one embodiment, DOCSIS A.M.P. receiver 318 may beimplemented via a system-on-chip (SOC) manufactured, for example, byBroadcom Corporation, and incorporated into the gateway modem 308. TheDOCSIS receiver 318, along with other components, may alternatively beimplemented externally to the gateway modem 308, as will be describedfurther in connection with FIG. 3B, according to embodiments of theinvention.

Simultaneously (or substantially simultaneously) to signal S3 beingpresented to receiver 318, signal S4 is supplied to a downconverter 320(e.g., block downconverter (BDC)), or alternative frequency conversiondevice, operative to receive, as an input, signals in a 258-454 MHzfrequency spectrum and to generate, as an output, correspondingdownconverted signals in a 54-258 MHz frequency spectrum. As a result ofthis downconversion process, downconverter 320 essentially places theupconverted signals supplied to gateway modem 308 back on their originalcarrier frequency where they are recombined with channels that did notneed to be upconverted because they reside normally on a carrierfrequency greater than 258 MHz. This recombination is preferablyperformed by an RF combiner 322 which is operative to receive thedownconverted signals generated by downconverter 320 and signal S2generated by first RF splitter 314 and to generate a combined signal, S5(e.g., combined programming material).

Optionally, combined signal S5 may be filtered to remove duplicateupconverted content, such as by using a first filter 323 coupled in aseries signal path to an output of the RF combiner 322. Alternatively(or in addition to), signal S2 may be optionally filtered, such as, forexample, using a second filter 321 coupled in a series signal pathbetween RF splitter 314 and RF combiner 322, to remove the duplicatecontent prior to being fed to the RF combiner. In accordance withanother embodiment, RF splitter 314 may be implemented as afrequency-selective splitter, thereby eliminating the need foradditional filters 321 and 323 to remove the duplicate upconvertedcontent.

Combined signal S5 is fed to a second diplex filter 324. Diplex filter324 includes a first port, port L, for conveying signals in a frequencyrange less than 42 MHz, a second port, port H, for conveying signals ina frequency range greater than 54 MHz, and a third port, port S, onwhich the first and second ports are multiplexed. As previously stated,each of the ports of diplex filter 324 is bidirectional. Signal S5,which comprises a combination of the downconverted signals output fromdownconverter 320 in the frequency range 54-258 MHz, and signal S2, inthe frequency range greater than 258 MHz, is supplied to port H ofdiplex filter 324. These signals are output on port S of diplex filter324 and are fed to a third diplex filter 326, or alternative CPEinterface, operatively coupled to the second diplex filter 324.

Diplex filter 326 includes a first port, port L, for conveying signalsin a frequency range less than 1002 MHz, a second port, port H, forconveying signals in a frequency range greater than 1125 MHz, and athird port, port S, on which the first and second ports are multiplexed.Port S of diplex filter 326 is connected to port S of diplex filter 324.In this manner, downstream signals in a frequency range from 54 MHz to1002 MHz are output on port L of diplex filter 326 and sent to CPE 304.This 54-1002 MHz frequency spectrum continues to support legacy servicewhere 54 MHz is the minimum frequency of the downstream signal path.

Diplex filter 326 additionally functions to separate Multimedia overCoax Alliance (MoCA®, a registered trademark of Multimedia Over CoaxAlliance, Inc.) signals received or transmitted by a MoCA transceiver332 which may be optionally included in gateway modem 308. MoCAtransceiver 332 is preferably a bidirectional time division multipleaccess (TDMA) device used for communicating with other MoCA devices inthe home. MoCA provides a specification for transporting digitalentertainment and information content over existing coaxial cable in thehome in the 1 GHz microwave band, using, for example, orthogonalfrequency division multiplexing (OFDM) modulation. (See, e.g.,Multimedia over Coax Alliance (MoCA) MAC/PHY v1.1 specification, October2007, the disclosure of which is incorporated herein by reference in itsentirety for all purposes). This cable can be used for providing dataconnections to televisions, set-top boxes, and other entertainmentdevices without the need to provide additional or new connections. Thetechnology underlying MoCA provides the elements necessary to use theexisting coaxial cable in the home to distribute high-quality multimediacontent and high-speed data, with throughput exceeding 100 Mbit/s(Mbps). The MoCA 1.0 and 1.1 specifications currently provide eight50-MHz wide channels beginning at a frequency of 1125 MHz and ending at1525 MHz.

Thus, while it is not required to include MoCA transceiver 332 ingateway modem 308, it is preferred in order to facilitate in-homenetworking between other MoCA-compliant devices in the home and the HFCnetwork 306, particularly where CPE 304 includes MoCA-capable devices.For example, MoCA signals having frequencies greater than 258 MHz fromthe HFC network 306 are output on port H of diplex filter 312. Thesesignals are split by RF splitter 314, a portion of which is passedthrough RF combiner 322 and fed to port H of diplex filter 324. The MoCAsignals are then fed to diplex filter 326 which separates the MoCAsignals having frequencies greater than 1125 MHz from other signalshaving frequencies less than 1002 MHz. The MoCA signals are output onport H of diplex filter 326 and subsequently sent to MoCA transceiver332 for further processing.

With continued reference to FIG. 3A, a upstream signal path through thegateway modem 308 will now be described, in accordance with anembodiment of the invention. Signals in the 5-42 MHz frequency bandtransmitted by one or more legacy devices (e.g., legacy STB or STT) inCPE 304 are received by port L of diplex filter 326, which is operativeto receive signals in the frequency range less than 1002 MHz (e.g., 5-42MHz). The signal received on port L of diplex filter 326 is multiplexedonto port S of diplex filter 326. This signal from CPE 304 (e.g., in thefrequency range 5-42 MHz) is then fed to port S of diplex filter 324which is operative to separate signals having frequencies less than 42MHz and to output this signal, S6, on port L of diplex filter 324.

Signal S6 output on port L of diplex filter 324 is fed to a RF combiner328 which is operative to combine signal S6 with an output signalgenerated by an advanced DOCSIS transmitter 330 (which may be referredto as a “DOCSIS A.M.P.” or, informally, a “DOCSIS 4.0” transmitter) togenerate a combined signal, S7. Combined signal S7 is supplied to port Lof diplex filter 312, which is adapted to receive signals in thefrequency range less than 200 MHz, and then multiplexed on port S ofdiplex filter 312. The combined signal S7 is then sent to HFC network306 for communication with the headend or hub 302 where the advancedupstream DOCSIS signals in the frequency spectrum less than 200 MHztransmitted by DOCSIS transmitter 330 are routed to an advanced cablemodem termination system (CMTS) and the legacy signals in the 5-42 MHzspectrum from CPE 304 are routed to a legacy system for furtherprocessing.

Although ideally there are no losses associated with the signal paths ingateway modem 308, in practice one or more components in the gatewaymodem will exhibit losses, such as, for example, the diplex filters 312,324 and 326, and the RF splitters/combiners 314, 322 and 328. There mayalso be losses associated with connection paths in the gateway modem308, although these losses should not be significant.

As indicated in table 350, RF losses in the signal path between theadvanced DOCSIS transmitter 330 and the HFC network 306 (D4 TX signalpath) are relatively low; namely, about 4.0 dB. These losses areattributable to the combiner 328 (about 3.5 dB) and one side (e.g., portL to port S) of diplex filter 312 (about 0.5 dB). The overall lossassociated with the D4 TX signal path is important since the cost oftransmitters capable of providing a 1 Gbps upstream data rate is heavilydependent upon the amount of power required; the amount of transmitpower required is, in turn, a direct function of the amount of loss inthe signal path. Alternatively, to reduce the loss of the D4 TX signalpath even further, combiner 328 may be replaced with a directionalcoupler which could save about another 2.0 dB. However, a directionalcoupler is typically more costly than a combiner, and hence the benefitin savings might not be as significant.

Other signal paths in the gateway modem 308 and their associated lossesare depicted in table 350. For example, the signal path between theadvanced DOCSIS receiver 318 and the HFC network 306 (D4 RX signalpath), which is essentially the same as the signal path between the HFCnetwork and the input to the block downconverter 320, has a loss ofabout 8.0 dB, attributable to one side (e.g., port S to port H) ofdiplex filter 312 (about 0.5 dB) and RF splitters 314 and 316 (about3.75 dB each). The legacy transmitter (Legacy TX) exhibits a loss ofabout 5 dB, not including other in-home signal splitters. This loss iseasily tolerated by the legacy transmitter which is designed to toleraterelatively high losses. The legacy receiver (Legacy RX) exhibits a lossof about 7 dB, not including other in-home signal splitters. Ifrequired, a conventional in-house amplifier (e.g., about $10-$20), whichmay already be present, can be used to offset this loss. An embodimentutilizing a stand-alone down-converter integrated with a type-D houseamplifier will be described herein below in conjunction with FIG. 4.

With reference to table 352, plant-facing spectrum access correspondingto certain signal paths in the gateway modem 308 is shown. The advancedDOCSIS transmitter signal path D4 TX includes port L of diplex filter312, and therefore will be limited to upstream signals havingfrequencies of less than 200 MHz (a corner frequency of the low-passfilter associated with port L of the diplex filter 312). Advantageously,in the future, when legacy upstream support is no longer required, nofurther modifications to the gateway modem topology according toembodiments of the invention will be needed. The advanced DOCSISreceiver signal path D4 RX includes port H of diplex filter 312, andtherefore will support any downstream signals having frequencies ofgreater than 258 MHz (a corner frequency of the high-pass filterassociated with port H of the diplex filter 312).

For legacy support, the legacy transmitter signal path in gateway modem308, which includes port L of diplex filter 324, is adapted for upstreamsignals having frequencies of less than 42 MHz (e.g., signals in therange 5-42 MHz). The legacy receiver signal path (which supports accessby legacy STB/STTs and legacy DOCSIS devices) is adapted for downstreamsignals in a first frequency range 54-258 MHz, which includes channels2-29, A-1:5, and STB OOB communications, and in a second frequency range462-870 MHz, which includes 15 analog channels (up to 552 MHz) and 53QAM channels.

The prescribed frequency value of 870 MHz set for the upper limit of theabove-noted second frequency range is indicative of the highest QAMchannel tunable by 100 percent of the present legacy STBs in a givensystem, and therefore it would not be useful to provide QAM capabilityabove this frequency. The prescribed frequency value of 462 MHz for thelower limit of the second frequency range is an artifact of the choiceof the down-conversion block (e.g., 54-258 MHz) and is a function of theselected block size. The prescribed frequency value of 258 MHzcorresponding to the upper limit of the first frequency range associatedwith the signal block to be up-converted is based on the assumption thatit takes about 30 percent of an octave to accomplish a diplex filteroperation (e.g., 200 MHz+30%≈258 MHz). The gap between the two frequencyranges is a result of the upconversion and downconversion processesassociated with the illustrated embodiment (e.g., block upconverter 310and block downconverter 320). It is to be understood, however, thatthese prescribed frequencies are merely illustrative and are notlimitations of the invention itself.

If, in place of an analog legacy STB, a digital-only STB (which may bereferred to herein as a “Baldur” receiver) is used having 1 GHz orhigher reception capability (e.g., 1002 MHz), according to anotherembodiment of the invention, the frequency gap can be reduced byeliminating the need to perform downconversion in the manner described,thereby increasing spectrum access. Digital-only receivers suitable foruse with the invention will be well-known by those skilled in the art,and furthermore the type of digital-only receiver employed is notcritical to the functioning of the invention. The digital-only receiversignal path (Baldur RX) is adapted for downstream signals in thefrequency range 54-258 MHz, which includes up to 33 QAM channels, and462-1002 MHz, which includes up to 90 QAM channels.

As previously stated, the present invention is not limited to thespecific frequency ranges shown in the figures and described herein. Byway of illustration only, FIG. 3B is a block diagram depicting at leasta portion of an exemplary broadband communications system 300 includinga gateway apparatus (e.g., modem) 309, according to another embodimentof the invention. System 300 is essentially the same as the systemdepicted in FIG. 3A, except that rather than receiving signals from HFCnetwork 306 in a 258-454 MHz spectrum, the gateway modem 309 depicted inFIG. 3B is adapted to receive signals from network 306 in the 798-1002MHz spectrum. To accomplish this, headend or hub 301 preferably includesan upconverter 311 operative to receive as an input signals in a 54-258MHz spectrum and to generate as an output corresponding upconvertedsignals in a modified 798-1002 MHz spectrum. By placing the upconvertedsignals above the maximum frequency of the former 258-454 MHz spectrumused in gateway modem 308 (FIG. 3A), gaps in the access spectrum caneffectively be eliminated, as shown by comparing legacy and digital-onlyreceiver access in table 352 shown in FIG. 3A with corresponding entriesin table 351 shown in FIG. 3B. With reference to table 351, the legacyreceiver (Legacy RX) and digital-only receiver (Baldur RX) signal pathsare adapted for downstream signals in a contiguous frequency range54-798 MHz for any application, including, for example, analog,out-of-band, or QAM signals.

Similarly, gateway modem 309 is essentially the same as the gatewaymodem 308 depicted in FIG. 3A, except that the block downconverter 319in the gateway apparatus is operative to receive, as an input, signalsin a 798-1002 MHz frequency spectrum and to generate, as an output,corresponding downconverted signals in a 54-258 MHz frequency spectrum.As a result of this downconversion process, downconverter 319essentially places the upconverted signals supplied to gateway modem 309back on their original carrier frequency where they are recombined withchannels that did not need to be upconverted because they residenormally on a carrier frequency greater than 258 MHz.

It is to be appreciated that the modified frequency range used in FIG.3B is also applicable to other embodiments of the invention shown (e.g.,illustrative embodiments depicted in FIGS. 3C, 4, 5 and 6) and describedherein. Furthermore, in accordance with alternative embodiments of theinvention, headend 302 need not convert any signals (or may only convertsome of the signals) to a different frequency spectrum. Rather, at leasta portion of the signals may be sent to gateway apparatus 309 (via HFCnetwork 306), without performing upconversion at the headend 302, andused at their original frequency locations.

FIG. 3C is a block diagram depicting at least a portion of anillustrative broadband communications system 300 including an exemplarysimplified gateway apparatus 360, according to an embodiment of theinvention. As previously stated in conjunction with gateway modem 308shown in FIG. 3A, DOCSIS A.M.P. receiver 318, as well as DOCSIS A.M.P.transmitter 330 and DOCSIS A.M.P. MoCA transceiver 332, may resideexternally, such as in a separate block 362 in operative communicationwith gateway apparatus 360. Thus, gateway apparatus 360 is essentiallythe same as gateway modem 308, except that the DOCSIS receiver 318,DOCSIS transmitter 330 and DOCSIS MoCA transceiver 332 have been removedtherefrom to simplify the gateway implementation.

Since the DOCSIS A.M.P. receiver 318, DOCSIS A.M.P. transmitter 330 andDOCSIS A.M.P. MoCA transceiver 332 all preferably utilize signals indisjoint (i.e., non-overlapping) frequency bands, gateway apparatus 360includes a triplex filter 364, which may be implemented as cascadeddiplex filters, which facilitates communication between the gatewayapparatus 360 and block 362 via a single communication link 366. Thetriplex filter 364 preferably includes a first port, port L, operativewith signals having a frequency less than 200 MHz, a second port, portM, operative with signals in a frequency range between 258 MHz and 1002MHz, a third port, port H, operative with signals having a frequencygreater than 1125 MHz, and a fourth port, port S, upon which ports L, M,or H are multiplexed. It is to be appreciated that the frequency rangesdescribed are merely illustrative, and that the invention is not limitedto any specific frequency or range of frequencies.

Specifically, signals transmitted by DOCSIS transmitter 330 to gatewayapparatus 360 are received on port S of triplex filter 364, viacommunication link 366, and sent to combiner 328 in gateway apparatus360 via port L of the triplex filter, and then sent to network 306.Signals from network 306 are split by RF splitter 316 in gatewayapparatus 360 are received on port M of triplex filter 364, and thensent to DOCSIS receiver 318. Likewise, signals passed between DOCSISMoCA transceiver 332 and gateway apparatus 360 are preferably conveyedusing ports S and H of the triplex filter 364.

As stated herein above, in order to compensate for losses associatedwith the legacy receiver signal path, one or more amplifiers can beadvantageously employed in the gateway apparatus. FIG. 4 is a blockdiagram depicting an exemplary broadband communications system 400including a gateway apparatus 408 comprising a plurality of integratedamplifiers, according to an embodiment of the invention. Like gatewaymodem 308 shown in FIG. 3A, gateway apparatus 408 is coupled to aheadend or hub 302 via a HFC network 306, or alternative communicationsarrangement (e.g., wide local area network (WLAN)). HFC network 306 ispreferably adapted to convey downstream signals (from headend 302 togateway apparatus 408) in the frequency range 258-1002 MHz and upstreamsignals (from gateway apparatus 408 to headend) in the frequency range5-200 MHz. As apparent from the figure, gateway apparatus 408, unlikegate modem 308 shown in FIG. 3A, does not include a DOCSIS transmitterand/or receiver, and may therefore be considered a standalonedownconverter. It is reiterated that the invention is not limited to thespecific frequencies or range of frequencies described herein.

In order to provide enhanced upstream data rates (e.g., 1 Gbps orhigher), the entire spectrum can be moved to the proposed 200/258 MHzsplit point using known upconversion techniques (block upconversion). Toaccomplish this, headend or hub 302 preferably includes an upconverter310 (e.g., block upconverter (BUC)) operative to receive input signalsin a 54-258 MHz spectrum and to generate as an output correspondingupconverted signals in a modified 258-454 MHz spectrum, as previouslyexplained. These upconverted signals are then passed to the HFC network306.

Gateway apparatus 408 is operative to receive the upconverted signalsfrom the HFC network 306. Specifically, a first RF splitter 412 in thegateway apparatus 408 is operative to receive the upconverted signalsfrom the HFC network 306. A first portion of the upconverted signals,S1, output from splitter 412 is fed to a first diplex filter 414 and asecond portion of the unconverted signals, S2, may be supplied to anembedded multimedia terminal adapter (eMTA), or other apparatus fordelivering broadband services to the home. An eMTA is beneficial forcombining delivery of high-speed data with Voice over Internet Protocol(VoIP) services by connecting legacy telephones and terminal equipment(e.g., a facsimile machines) to a multiple system operator's (MSO's)enhanced IP network.

Diplex filter 414 is operative to receive signal S1 from splitter 412 atport S thereof. Since signal S1 has been upconverted and thereforeincludes components in the 258-454 MHz frequency spectrum, this signalwill be multiplexed onto port H of diplex filter 414. As previouslydescribed, a diplex filter operatively separates a signal received onits S port into two component portions as a function of frequency; afirst portion comprising signals above a first prescribed frequency(e.g., 258 MHz) are output on port H and a second portion comprisingsignals below a second prescribed frequency (e.g., 200 MHz) are outputon port L of the filter.

The downstream signal output on port H of diplex filter 414 is sent to asecond RF splitter 416 where the signal is split to generate third andfourth signals, S3 and S4, respectively. Splitter 416 may also beimplemented as a directional coupler, according to another embodiment.Signal S3 is supplied to a downconverter 418 (e.g., block downconverter(BDC)) operative to receive as an input signals in a 258-454 MHzspectrum and to generate, as an output, corresponding downconvertedsignals in a 54-258 MHz spectrum. As a result of this downconversionprocess, downconverter 418 essentially places the upconverted signalssupplied to gateway apparatus 408 back on their original carrierfrequency where they are recombined with channels that did not need tobe upconverted because they originally reside on a carrier frequencygreater than 258 MHz. This recombination is preferably performed by anRF combiner 419 which is operative to receive the downconverted signalsgenerated by downconverter 418 and signal S4 generated by second RFsplitter 416 and to generate a combined signal, S5. Optionally, combinedsignal S5 may be filtered to remove duplicate upconverted material.

Combined signal S5 is fed to a first amplifier 420, which may be atype-D house amplifier or the like. Amplifier 420 is preferablyconfigured having a gain that at least compensates for losses in thedownstream signal path attributable to, for example, blockupconversion/downconversion (e.g., block upconverter 310, blockdownconverter 418), diplex filter 414, and splitters 412 and 416. Thegain of amplifier 420 may also compensate for losses associated withsplitters 426, 428 and 430, generally about 4 dB per split. For example,a 4-way signal split (as shown) would typically exhibit a loss of about8 dB in each signal path. The gain of amplifier 420 may be programmablein other embodiments to account for variability in the downstream signalpath. While only one amplifier 420 is shown, it is to be understood thatmore than one amplifier circuit may be used (e.g., cascaded in series),with the gain of each amplifier adjusted accordingly to provide aprescribed overall gain in the signal path.

With regard to losses in general, a determination of losses in thesystem is beneficial in that losses in front of a gain block (e.g.,amplifiers 420 and 432) generally worsen overall noise performance inthe system. It is therefore desirable to minimize losses in a givensignal path prior to the gain block.

The amplified signal generated by amplifier 420 is fed to port H of asecond diplex filter 422 adapted for receiving signals in a frequencyrange greater than 54 MHz. This signal is output on port S of diplexfilter 422 and then supplied to a low-pass filter (LPF) 424. LPF 424 isconfigured having a corner frequency of 1002 MHz, and is thereforeoperative to pass frequencies below 1002 MHz and to attenuate signalcomponents above 1002 MHz. LPF 424 is operative to minimize MoCA energyon the cable TV feeder and to prevent interference between homes thatuse MoCA technology. LPF 424 also acts as a reflector to minimize lossof the MoCA signal within the home. The filter signal generated by LPF424 is preferably split using one or more RF splitters 426, 428 and 430,and supplied to CPE, including STBs and TV outlets.

For the upstream signal path, a signal from one or more STBs in the homeis supplied to the one or more splitters 426, 428 and 430, and passedthrough LPF 424 to remove, or substantially attenuate, signal componentsgreater than 1002 MHz (e.g., noise, etc.). The filtered upstream signalis then fed to port S of diplex filter 422. Since upstream signalsoccupy the frequency spectrum less than 42 MHz, this signal is sent toport L of diplex filter 422. This signal output on port L is thenamplified by a second amplifier 432, which again may be a type-D houseamplifier or an alternative amplifier. The amplified signal generated byamplifier 432 is sent to port L of diplex filter 414 where it ismultiplexed onto port S of filter 414 and subsequently passed, throughsplitter 412, to HFC network 306.

Amplifier 432 is preferably configured having a gain that at leastcompensates for losses in the upstream signal path attributable to, forexample, RF splitters 426, 428 and 430 and diplex filter 422, as well asother losses that may be present in the upstream signal path (e.g.,diplex filter 414 and splitter 412). The gain of amplifier 432 may beprogrammable in other embodiments to account for variability in theupstream signal path. As in the case with amplifier 420, while only oneamplifier 432 is shown, it is to be understood that more than oneamplifier circuit may be used (e.g., cascaded in series), with the gainof each amplifier adjusted accordingly to provide a prescribed overallgain in the signal path. By controlling the amounts of gain inamplifiers 420 and 432, the split ratios of splitters 412, 416, 419,426, 428 and 430 can be beneficially configured as desired.

In table 450, RF losses in the respective signal paths between each port(except the eMTA port) and the HFC network 306 are indicated. Theselosses are attributable to components in the signal paths, including,for example, the splitters 416, 426, 428 and 430, diplex filters 414 and422, LPF 424, and combiner 412. The overall loss associated with thelegacy transmitter signal path (Legacy TX) for upstream signals is abouta uniform 6 dB, and for downstream signals in the legacy receiver signalpath (Legacy RX) there is a uniform gain (for about 75 feet of RG-6coaxial cable.

With reference to table 452, plant-facing spectrum access correspondingto certain signal paths in the gateway apparatus 408 is shown. Thelegacy transmitter signal path (Legacy TX) in gateway apparatus 408,which includes port L of diplex filters 414 and 422, is adapted forupstream signals having frequencies of less than 42 MHz (e.g., signalsin the range 5-42 MHz). The legacy receiver signal path (Legacy RX) isadapted for downstream signals in the frequency range 54-258 MHz, whichincludes channels 2-29, A-1:5, and STB OOB communications, and 462-870MHz, which includes 15 analog channels (up to 552 MHz) and 53 QAMchannels. The gap between the two frequency ranges is a result of theupconversion and downconversion processes associated with theillustrated embodiment (e.g., block upconverter 310 and blockdownconverter 418). If, in place of an analog legacy STB, a digital-onlySTB (e.g., Baldur receiver) is used having 1002 MHz receptioncapability, according to another embodiment of the invention, thefrequency gap can be reduced by eliminating the need to performdownconversion in the manner described, thereby increasing spectrumaccess. The Baldur receiver signal path (Baldur RX) is adapted fordownstream signals in the frequency range 54-258 MHz, which includes upto 33 QAM channels, and 462-1002 MHz, which includes up to 90 QAMchannels.

As stated above, the eMTA port coupled to splitter 412 is preferably anexception to the losses set forth in tables 450 and 452 corresponding tothe gateway apparatus 408. Specifically, the eMTA port is purposefullylocated such that in the event of a power failure or other scenario inwhich the gain blocks (e.g., amplifiers 420 and 432) in gatewayapparatus 408 stopped functioning, the eMTA port essentially avoids thelosses attributable to the various splitters, etc., in the gatewayapparatus, thereby allowing a telephone or other device coupled tonetwork 306 via the eMTA port to continue functioning, assuming thedevice had its own local power source (e.g., battery backup). Thus, theeMTA port advantageously does not require operation of the gain blocksin the gateway apparatus 408.

FIG. 5 is a block diagram depicting an exemplary broadbandcommunications system 500 including an illustrative gateway apparatus508, according to an embodiment of the present invention. Gatewayapparatus 508 is suitable for use, for example, in homes that do notemploy advanced media access control (MAC) and physical (PHY) layerDOCSIS devices, only legacy CPE 304 (e.g., legacy STBs or STTs). Thisembodiment is essentially a simplified version of gateway apparatus 408shown in FIG. 4. As in the other embodiments described herein above, itis to be appreciated that the invention is not limited to the specificfrequencies or range of frequencies shown.

As apparent from FIG. 5, gateway apparatus 508 is coupled to HFC network306 and is operative as an interface between the HFC network and CPE304, which preferably includes one or more legacy devices in the home.HFC network 306, in turn, is in communication with headend 302 and isadapted to receive downstream signals therefrom that have beenupconverted, by upconverter 310 or alternative upconversion means, froma 54-258 MHZ frequency spectrum to a 258-454 MHz frequency spectrum, aspreviously explained.

Gateway apparatus 508 is operative to receive the upconverted signalsfrom the HFC network 306. More particularly, a first diplex filter 512in gateway apparatus 508 is operative to receive the upconverted signalsfrom the HFC network 306. Diplex filter 512 includes a first port, portL, for conveying signals in a frequency range less than 42 MHz, a secondport, port H, for conveying signals in a frequency range greater than258 MHz, and a third port, port S, on which the first and second portsare multiplexed. Diplex filter 512 is operative to divide forward andreverse signals received from and transmitted to, respectively, HFCnetwork 306; downstream signals in a frequency range greater than 258MHz received from the HFC network, coupled to port S of the filter, aresent to port H and upstream signals in a frequency range less than 200MHz are received on port L of the filter and multiplexed onto port S fortransmission to the HFC network.

Downstream signals output on port H of diplex filter 512 are fed to a RFsplitter 514 which is operative to generate at least two signals havingsubstantially equal amplitudes and phase relative to one another. One ofthe split signals, S1, generated by RF splitter 514 is supplied to adownconverter 516 (e.g., a block downconverter) operative to receive, asan input, signals in a 258-454 MHz frequency spectrum and to generate,using known downconversion techniques, corresponding downconvertedsignals in a 54-258 MHz frequency spectrum. As a result of thedownconversion process, downconverter 516 essentially places theupconverted signals supplied to gateway apparatus 508 back onto theiroriginal carrier frequency where they are recombined with another splitsignal, S2, generated by RF splitter 514. Signal S2 may include channelsthat originally reside on a carrier frequency greater than 258 MHz andtherefore do not require upconversion; in this instance, downconversionof these channels (such as by downconverter 516) to their originalcarrier frequencies can be omitted (bypassed). The recombination ofsignal S2 with the downconverted signal is preferably carried out usingan RF combiner 518, or alternative combination means, operative toreceive the downconverted signals, generated by downconverter 516, andsignal S2, generated by RF splitter 514, and to generate a combinedsignal, S3. Optionally, signal S3 may be filtered to remove duplicateupconverted material.

Combined signal S3 is fed to a second diplex filter 520. Diplex filter520 includes a first port, port L, for conveying signals in a frequencyrange less than 42 MHz, a second port, port H, for conveying signals ina frequency range greater than 54 MHz, and a third port, port S, onwhich the first and second ports are multiplexed. As previously stated,each of the ports of diplex filter 520 is bidirectional. Signal S3,which comprises a combination of the downconverted signals output fromdownconverter 516 in the frequency range 54-258 MHz, and signal S2, inthe frequency range greater than 258 MHz, is supplied to port H ofdiplex filter 520. These signals are output on port S of diplex filter520 which is coupled to legacy devices in CPE 304 (e.g., legacy STB).

Upstream signals from CPE 304 are, similarly, sent to port S of diplexfilter 520 where, being in a 5-42 MHz frequency spectrum, are output onport L of filter 520. These signals are then supplied to port L ofdiplex filter 512 where they are passed to HFC network 306. As apparentfrom FIG. 5, upstream signals do not pass through a splitter.Consequently, overall losses associated with the upstream signal path ingateway apparatus 508 are less compared to the gateway modem 308 shownin FIG. 3A. For example, as indicated in table 550, overall lossescorresponding to the legacy transmitter signal path (Legacy TX) ingateway apparatus 508 are about 1 dB (plus other in-home splits)compared to about 5 dB for the legacy transmitter signal path in gatewaymodem 308. Losses corresponding to the legacy receiver signal path(Legacy RX) in gateway apparatus 508 are essentially the same as thelosses for the legacy receiver signal path in gateway modem 308; namely,about 7 dB.

With regard to spectrum access of the signal paths in gateway apparatus508, plant-facing spectrum access for gateway apparatus 508, asindicated in table 552, is essentially the same as for the gatewayapparatus 408 shown in FIG. 4. Specifically, the legacy transmittersignal path in gateway apparatus 508, which includes port L of diplexfilters 512 and 520, is adapted for upstream signals having frequenciesof less than 42 MHz (e.g., signals in the frequency range 5-42 MHz). Thelegacy receiver signal path is adapted for downstream signals in thefrequency range 54-258 MHz, which includes channels 2-29, A-1:5, and STBOOB communications, and 462-870 MHz, which includes 15 analog channels(up to 552 MHz) and 53 QAM channels. As previously explained, the gapbetween the two frequency ranges is primarily a result of theupconversion and downconversion processes associated with theillustrated embodiment (e.g., block upconverter 310 and blockdownconverter 516). If, in place of an analog legacy STB, a digital-onlySTB (e.g. “Baldur” receiver) is employed, according to anotherembodiment of the invention, the frequency gap can be reduced byeliminating the need to perform downconversion in the manner described,thereby increasing spectrum access. The Baldur receiver signal path(Baldur RX) is adapted for conveying downstream signals in the frequencyrange 54-258 MHz (up to 33 QAM channels) and 462-1002 MHz (up to 90 QAMchannels).

In the various illustrated embodiments of the invention describedherein, the gateway apparatus (e.g., 308, 408, 508) is shown as aseparate functional block from the CPE 304. It is to be appreciated,however, that the gateway apparatus, or portions thereof, may beincorporated within CPE 304 (e.g., within a STB). Additionally, one ormore functional blocks shown in the illustrated embodiments of FIGS. 3-5may be combined into one another or into a different functional block;the depictions herein are not intended to limit the actual physicalimplementation of the apparatus in any way. For example, diplex filters324 and 326 in the gateway modem 308 shown in FIG. 3A may beadvantageously combined into one four-port filter (e.g., quadruplexfilter or “quadruplexer”). Likewise, RF splitters 314 and 316 may becombined into a single three-way splitter, as will become apparent tothose skilled in the art given the teachings herein.

Techniques of the invention described herein may be performed usinghardware and/or software aspects. Software includes, but is not limitedto, firmware, resident software, microcode, etc. By way of illustrationonly, according to an embodiment of the invention at least a portion ofthe receiver in gateway modem 308 may be implemented using a broadbanddigital direct downconversion receiver suitable for software-definedradio. (See, e.g., Mohamed Ratni et al., “Broadband Digital Direct DownConversion Receiver Suitable for Software Defined Radio,” 13th IEEE Int.Symposium on Personal, Indoor and Mobile Radio Communications PIMRC,Lisbon, Portugal, September 2002, pp. 93-99, the disclosure of which isincorporated herein by reference in its entirety for all purposes). Forexample, signals (e.g., from HFC network 306) can be received using anyband, or they can be received in QAM and then using software techniquesthe corresponding analog versions can be synthesized therefrom.

One or more embodiments of the invention or elements thereof may beimplemented in the form of an article of manufacture including a machinereadable medium that contains one or more programs which when executedimplement such step(s); that is to say, a computer program productincluding a tangible computer readable recordable storage medium (ormultiple such media) with computer usable program code for performingthe method steps indicated. Furthermore, one or more embodiments of theinvention or elements thereof can be implemented in the form of anapparatus including a memory and at least one processor that is coupledto the memory and operative to perform, or facilitate performance of,exemplary method steps.

Yet further, in another aspect, one or more embodiments of the inventionor elements thereof can be implemented in the form of means for carryingout one or more of the method steps described herein; the means caninclude (i) hardware module(s), (ii) software module(s) executing on oneor more hardware processors, or (iii) a combination of hardware andsoftware modules; any of (i)-(iii) implement the specific techniques setforth herein, and the software modules are stored in a tangiblecomputer-readable recordable storage medium (or multiple such media).Appropriate interconnections via bus, network, and the like can also beincluded.

Aspects of the invention may be particularly well-suited for use in anelectronic device or alternative system (e.g., broadband communicationssystem). For example, FIG. 6 is a block diagram depicting an exemplaryprocessing system 600 formed in accordance with an aspect of theinvention. System 600, which may represent, for example, a gatewayapparatus or a portion thereof, may include a processor 610, memory 620coupled to the processor (e.g., via a bus or alternative connectionmeans), as well as input/output (I/O) circuitry, of which display 630 isrepresentative, operative to interface with the processor. The processor610 may be configured to perform at least a portion of the functions ofthe present invention (e.g., by way of one or more processes 640 whichmay be stored in memory 620), illustrative embodiments of which areshown in the previous figures and described herein above.

It is to be appreciated that the term “processor” as used herein isintended to include any processing device, such as, for example, onethat includes a central processing unit (CPU) and/or other processingcircuitry (e.g., network processor, digital signal processor (DSP),microprocessor, etc.). Additionally, it is to be understood that aprocessor may refer to more than one processing device, and that variouselements associated with a processing device may be shared by otherprocessing devices. The term “memory” as used herein is intended toinclude memory and other computer-readable media associated with aprocessor or CPU, such as, for example, random access memory (RAM), readonly memory (ROM), fixed storage media (e.g., a hard drive), removablestorage media (e.g., a diskette), flash memory, etc. Furthermore, theterm “I/O circuitry” as used herein is intended to include, for example,one or more input devices (e.g., keyboard, mouse, etc.) for enteringdata to the processor, and/or one or more output devices (e.g., display,etc.) for presenting the results associated with the processor.

Accordingly, an application program, or software components thereof,including instructions or code for performing the methodologies of theinvention, as described herein, may be stored in one or more of theassociated storage media (e.g., ROM, fixed or removable storage) and,when ready to be utilized, loaded in whole or in part (e.g., into RAM)and executed by the processor. In any case, it is to be appreciated thatat least a portion of the components shown in the previous figures maybe implemented in various forms of hardware, software, or combinationsthereof (e.g., one or more DSPs with associated memory,application-specific integrated circuit(s), functional circuitry, one ormore operatively programmed general purpose digital computers withassociated memory, etc). Given the teachings of the invention providedherein, one of ordinary skill in the art will be able to contemplateother implementations of the components of the invention.

At least a portion of the illustrative techniques of the presentinvention may be implemented in an integrated circuit. In formingintegrated circuits, die are typically fabricated in a repeated patternon a surface of a semiconductor wafer. Each of the die includes a devicedescribed herein, and may include other structures or circuits.Individual die are cut or diced from the wafer, then packaged asintegrated circuits. One skilled in the art would know how to dicewafers and package die to produce integrated circuits. Integratedcircuits so manufactured are considered part of this invention.

Although illustrative embodiments of the present invention have beendescribed herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments, and that various other changes and modifications may bemade by one skilled in the art without departing from the scope orspirit of the invention.

What is claimed is:
 1. An apparatus for interfacing between one or morecustomer premises devices and a communications network, the apparatuscomprising: an interface couplable to the communications network andoperative to receive at least first signals in a first downstreamfrequency band having a first minimum frequency defining at least aportion of a first upstream/downstream split point; a frequencyconverter coupled to the interface and operative to translate one ormore of the first signals from the first downstream frequency band toone or more translated first signals in a second downstream frequencyband having a second minimum frequency less than the first minimumfrequency, the first and second downstream frequency bands beingnon-overlapping; and a combiner coupled to the frequency converter andto the interface, the combiner being operative to combine the one ormore translated first signals in the second downstream frequency bandwith one or more of the first signals in the first downstream frequencyband to generate combined programming material having the second minimumfrequency defining at least a portion of a second upstream/downstreamsplit point for reception by one or more receiving location devices,wherein the interface comprises first and second diplex filters, thefirst diplex filter including a first port coupled to the frequencyconverter and to the combiner, a second port coupled to a first port ofthe second diplex filter, and a third port coupled to the communicationsnetwork, the second diplex filter including a second port coupled to theone or more receiving location devices, and a third port coupled to thecombiner, each of the first and second diplex filters being operative tomultiplex a corresponding one of the first and second ports onto thethird port thereof as a function of a frequency of respective signals onthe corresponding first and second ports.
 2. The apparatus of claim 1,further comprising at least one filter coupled in a series signal pathbetween the interface and the one or more receiving location devices,the at least one filter being operative to remove duplicate content fromthe combined programming material.
 3. The apparatus of claim 1, furthercomprising at least a first amplifier coupled in series in a signal pathbetween the communications network and the one or more receivinglocation devices, the first amplifier being operative to generate anamplified output signal having a gain that is adapted to at leastpartially compensate for one or more signal losses in the signal path.4. The apparatus of claim 3, wherein the first amplifier includes aninput operative to receive the combined programming material and anoutput operative to generate the amplified output signal for receptionby the one or more receiving location devices.
 5. The apparatus of claim3, wherein the first amplifier includes an input operative to receive atleast second signals comprising upstream data in an upstream frequencyband for transmission to the communications network, the firstdownstream frequency band, the second downstream frequency band and theupstream frequency band being non-overlapping, and an output operativeto generate the amplified output signal for transmission to thecommunications network.
 6. The apparatus of claim 1, further comprisinga transceiver coupled to the interface, the transceiver being operativeto facilitate communications between a plurality of the one or morereceiving location devices using a prescribed communications protocol.7. The apparatus of claim 6, wherein the prescribed communicationsprotocol comprises Multimedia over Coax Alliance (MoCA).
 8. Theapparatus of claim 1, further comprising a data-over-cable serviceinterface specification (DOCSIS) advanced media access control (MAC) andphysical layer (PHY) (A.M.P.) receiver coupled to the interface andoperative to receive DOCSIS signals from the communications network. 9.The apparatus of claim 1, further comprising a data-over-cable serviceinterface specification (DOCSIS) advanced media access control (MAC) andphysical layer (PHY) (A.M.P.) transmitter coupled to the interface andoperative to transmit DOCSIS signals to the communications network. 10.An apparatus for interfacing between one or more customer premisesdevices and a communications network, the apparatus comprising: aninterface couplable to the communications network and operative toreceive at least first signals in a first frequency band; a frequencyconverter coupled to the interface and operative to translate one ormore of the first signals from the first frequency band to one or moretranslated first signals in a second frequency band, the first andsecond frequency bands being non-overlapping; and a combiner coupled tothe frequency converter and to the interface, the combiner beingoperative to combine the one or more translated first signals in thesecond frequency band with one or more of the first signals in the firstfrequency band to generate combined programming material for receptionby one or more receiving location devices, wherein the interfacecomprises first and second diplex filters, the first diplex filterincluding a first port coupled to the frequency converter and to thecombiner, a second port coupled to a first port of the second diplexfilter, and a third port coupled to the communications network, thesecond diplex filter including a second port coupled to the one or morereceiving location devices, and a third port coupled to the combiner,each of the first and second diplex filters being operative to multiplexa corresponding one of the first and second ports onto the third portthereof as a function of a frequency of respective signals on thecorresponding first and second ports.